On Tue, Nov 13, 2012 at 05:27:17PM +0100, Peter Lieven wrote: > > Am 13.11.2012 um 17:26 schrieb Michael S. Tsirkin: > > > On Tue, Nov 13, 2012 at 05:21:50PM +0100, Peter Lieven wrote: > >> On 13.11.2012 17:22, Michael S. Tsirkin wrote: > >>> On Tue, Nov 13, 2012 at 12:49:03PM +0100, Peter Lieven wrote: > >>>> On 09.11.2012 19:03, Peter Lieven wrote: > >>>>> Remark: > >>>>> If i disable interrupts on CPU1-3 for virtio the performance is ok > >>>>> again. > >>>>> > >>>>> Now we need someone with deeper knowledge of the in-kernel irqchip and > >>>>> the > >>>>> virtio/vhost driver development to say if this is a regression in > >>>>> qemu-kvm > >>>>> or a problem with the old virtio drivers if they receive the interrupt > >>>>> on > >>>>> different CPUs. > >>>> anyone? > >>> Looks like the problem is not in the guest: I tried ubuntu guest > >>> on a rhel host, I got 8GB/s with vhost and 4GB/s without > >>> on a host to guest banchmark. > >> which ubuntu version in the guest? > >> > >> Peter > > > > ubuntu-10.04.4-server-amd64.iso > > can you try with vnet_hdr=on on the nic.
You mean on tap? Same thing. > the bug seems to be only relevant when vhost-net is used. > > Dietmar, see you implications with normal virtio? > > Peter